Switch operated by snap-acting diaphragm having an eccentrically located cam for manually operating the switch



3,436,503 AVING AN F. O. MOODY ERATED BY SN Aprll 1, 1969 SWITCH OPAP-ACTING DIAPHRAGM H ECCENTRICA CATED CAM FOR MANUAL NG THE SWITCH LLYLO OPERATI Sheet Filed Feb. 2, 1967 Y Wqya Mz/aa/ v I ATTORNEY April 1,1969 F. o. MOODY 3,

SWITCH OPERATED BY SNAP-ACTING DIAPHRAGM HAVING AN ECCENTRICALLY LQCATEDCAM FOR MANUALLY OPERATING THE SWITCH Filed Feb. 2, 1967 Sheet 012 Ill1N VEN'TOR.

ATTORNEY United States Patent Office 3,436,503 SWITCH OPERATED BYSNAP-ACTING DIA- PHRAGM HAVING AN ECCENTRICALLY LOCATED CAM FOR MANUALLYOPERAT- ING THE SWITCH Floyd 0. Moody, Dayton, Ohio, assignor to GeneralMotors Corporation, Detroit, Mich., a corporation of Delaware Filed Feb.2, 1967, Ser. No. 613,572 Int. Cl. H01h 35/40 US. Cl. 200-83 3 ClaimsABSTRACT OF THE DISCLOSURE In the preferred form, one wall of anenclosed fluid pressure chamber is formed of a shallow frusto-sphericalthin spring metal snap acting diaphragm. The enclosed chamber is mountedupon a support. The support has a passage through which a followerextends from the central portion of the diaphragm to a leaf springcontact for moving said contact member into engagement with acooperating contact. A rotatable cup-shaped housing surrounds thecontacts and is threaded upon the support. This housing carries atransverse leaf spring through which extends an exposed adjusting screwextending in alignment with and into contact with the followercontacting the leaf spring contact. The rotatable housing also isprovided with an eccentrically located cam for manually operating theleaf spring contact.

This invention pertains to pressure operated snap-acting switches for avariety of temperature controlling and pressure controlling apparatus.

It is an object of this invention to provide a simple inexpensivereliable pressure operated switch in which the operating diaphragm notonly provides the pressure actuation but also provides snap action in avery simple arrangement.

This and other objects are attained in the form shown in the drawings inwhich the operating diaphragm is 'ormed in a shallow frusto-sphericalshape so that it is 1 th pressure responsive and snap acting.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred embodiment of the present invention isclearly shown.

In the drawings:

FIGURE 1 is a perspective view of a snap-acting switch embodying oneform of my invention;

FIGURE 2 is a broken horizontal sectional view through the switch shownin FIGURE 1 taken generally along the line 2-2 of FIGURE 3;

FIGURE 3 is a transverse vertical sectional view taken along the line3-3 of FIGURE 2;

FIGURE 4 is a vertical sectional view taken along the line 4-4 of FIGURE2;

FIGURE 5 is an irregular vertical sectional view taken along the line 55of FIGURE 2; and

FIGURE 6 is a fragmentary vertical sectional view taken along the line6-6 of FIGURE 2.

Referring now to the drawings and more particularly to FIGURES 1 through3, there is illustrated a snap-acting switch 20 including an insulatedsupport 22 composed of a lower portion 24 and an upper portion 26. Thelower portion 24 has fastened to it a fluid motor 28 comprising a lowerhousing 30 of thick metal such as copper, brass, or stainless steel andthe snap-acting diaphragm 32 embodying my invention is formed of verythin spring metal such as .005 beryllium copper. The

Patented Apr. 1, 1969 downturned edges 34 of the snap-acting diaphragm32 are held between the rim 36 of the lower housing 30 and the rim 38 ofthe ring-shaped member 40. The rims 36, 34 and 38 are all offset andnest together. The rim 38 is sealed to the rim 36 by solder or any othersuitable joining material or plastic. The diaphragm 32 has a shallowcentral frusto-spherical portion which is stable only in the positionsshown in FIGURES 3 to 5. FIG URES 3 and 4 show the low stable positionwhile FIG- URE 5 shows the upper stable position. Between thesepositions the effect of the frusto-spherical shape will cause it to snapfrom one of these positions to the other position.

The ring-shaped member 40 is provided with a pair of upwardly extendinginverted L-shaped projections 42 each having an extruded threadedaperture receiving one of the screws 44 which extends through the upperportion and lower portion 26 and 24 of the support 22 as shown in FIGURE4 and are threaded into the aperture in the projections 42. These screws44 hold together the upper and lower portions 26 and 24 of the support22 and fastens them to the fluid motor 28. The lower portion 24 isprovided with a coaxially aligned aperture which receives a pin typeinsulated follower 46 bearing on the upper surface of the diaphragm 32.The upper surface of the follower 46 bears against the bottom of thespring contact member 48 provided with a double contact at the right endof FIGURE 3 and having an anchored left end portion on top of theinverted L-shaped terminal 50. The bottom of the contact member 48 andthe terminal 50 are provided with aligned apertures which receive theupwardly extending projection 52 extending upwardly from the lowerhousing 24 into the aligned aperture in the upper housing 26. The lowerhousing portion 24 is provided with a notch for receiving the adjacentportion of the terminal 50. The opposite or free right end of thecontact member 48 has its double contacts operating between a lowercontact 54 and an upper contact 56 so that the switch can be used as adouble throw switch. Each of these terminals are in the form of aninverted bent L- shape as is better shown in FIGURE 2. The downwardlyprojecting terminals 54 and 56 are separated sufficiently to provideadequate separation of the conductors as better shown in FIGURES 2 and5. The contact terminal 56 is lodged in a notch in the bottom face ofthe upper housing member 26 and has an aperture receiving the projectingpin 53. The contact terminal 54 is lodged in a notch in the upper faceof the lower housing member 24 and has an aperture receiving theprojecting pin 21.

To provide for calibration and adjustment of the switch 48, there isprovided a small upper cup-shaped plastic follower 58 which is slidablymounted in a coaxial aperture in the upper housing portion 26. Anadjusting screw 60 has at its lower end a pin which projects into thefollower 58. This adjusting screw 60 extends through a central aperturein the transverse leaf spring 62 and is threaded through an extrudedaperture 64 in the nut 66 having upturned lips engaging the sides of thetransverse leaf spring 62. The ends of the leaf spring 62 are supportedand held by a pair of downwardly extending projections 68 upon therotatable housing 70. The housing 70 is provided with a centrallylocated aperture 74 slightly larger than the head of the screw 60 sothat the screw can be turned by a screwdriver even though it is recessedin the housing 70. The housing 70 is provided with an annular flange 76which is threaded onto the rim of the upper housing portion 26 by coarsehelical threads. The housing 70 is also provided with a rim 78 by whichit may be turned upon the threaded engagement between the rim of theupper housing support 26. The rim 78 may be held stationary while thescrew 60 is turned to provide an initial factory set adjustment 3 forthe switch 48. Further adjustment of the switch 48 may be made at anytime by turning the rim 78 of the housing 70. This moves the housing '70toward or away from the switch member 48 and the diaphragm 32 to providethe customary adjustment of the spring and switch.

For holding the switch contact 48 in its lower position in contact withthe lower contact 54, there is provided an additional aperture in theupper housing portion 26 through which extends the follower 80. Therotatable housing 70 is provided with an integral downwardly projectingcam 82 provided with an inclined cam surface 84 which is adapted toengage and depress the follower 80 as shown in FIGURE 6 to keep themovable spring contact member 48 in its lower position when the cam 84is moved over the follower 80.

The fluid motor 28 may have its interior connected by a tube 86 to asource of pressure or the tube may be charged with a 'volatile liquidand sealed so that it is temperature responsive and makes the switchtemperature responsive as well as pressure responsive. The diaphragm 32may be made of some suitable very thin spring materials such asberyllium copper, phosphorus bronze or spring steel or any stainlesssteel having good spring characteristics. The housing member 70 and thesupport 22 may be made of a suitable plastic such as nylon, orpolypropylene or acetyl formaldehyde.

While the embodiment of the invention as herein disclosed constitutes apreferred form, it is to be understood that other forms might beadopted.

What is claimed is as follows:

1. A fluid pressure-operated switch including a support means, a switchmeans mounted upon said support means, said fluid motor including adiaphragm containing a cupshaped dent exposed to the pressure of thefluid in the motor and having its central portion inherently movablewith a snap action, said support means being provided with a wall ofelectrical insulating material between said switch mean sand saiddiaphragm, said wall being provided with an aperture and an insulatedoperable connection extending through said aperture between said centralportion and said switch means for operating said switch means to openand closed positions, a rototable housing surrounding and substantiallyenclosing the side of said support means opposite said fluid motor, saidrotatable housing having an axis of rotation and said housing and saidsupport means being provided with interengaging helical threadscoaxially arranged relative to the axis of rotation of said housing, aspring means having one portion mounted upon and rotatable with saidrotatable housing, an adjusting screw located upon the axis of saidrotatable mounting having a threaded connection with another portion ofsaid spring means, a follower of electrical insulating material operablyconnecting said adjusting screw and said switch means substantiallycoaxial with said adjusting screw, said rotatable housing having anaperture providing access to said ad- .4 justing screw for adjusting theoperation of said switch means.

'2. A fluid pressure-operated switch including a support means, a switchmeans mounted upon said support means, wherein the improvement comprisesa fluid motor mounted upon one side of said support means, said fluidmotor including a diaphragm containing a cup-shaped dent exposed to thepressure of the fluid in the motor and having its central portioninherently movable with a snap action, said support means being providedwith a wall of electrical insulating material between said switch meansand said diaphragm, said wall being provided with an aperture and aninsulated operable connection extending through said aperture betweensaid central portion of said diaphragm and said switch means foroperating said switch means to open and closed positions, a rotatableadjustable housing surrounding and substantially enclosing the side ofsaid support means opposite said fluid motor, said rotatable housinghaving an axis of rotation and said housing and said support means beingprovided with inter-engaging helical threads coaxially arranged relativeto the axis of rotation of said housing, a leaf spring having an endportion mounted on the inside of and rotatable with said rotatablehousing and having a portion free to yield relative to said housing, anadjusting screw having a threaded connection with the free portion ofsaid leaf spring located upon the axis of said rotatable housing, and afollower of electrical insulating material operably connecting saidadjusting screw and said switch means substantially coaxial with saidadjusting screw for adjusting the operation of said switch means.

3. A fluid pressure-operated switch including a support means, a switchmeans mounted upon said support means, a fluid motor mounted upon saidsupport means, said fluid motor including a diaphragm containing acup-shaped dent exposed to the pressure of the fluid in the motor andhaving its central portion inherently movable with a snap action, ininsulated operable connecting means extending between said centralportion and said switch means for operating said switch means to openand closed positions, wherein the improvement comprises a rotatablehousing surrounding and substantially enclosing one side of said supportmeans, said rotatable housing being provided with an eccentricallylocated cam, said support means being provided with means cooperatingwith said cam for operating said switch means.

References Cited UNITED STATES PATENTS 1,781,287 11/1930 Mayo ZOO-183.2X-R 2,103,214 12/ 1937 Coflin 210O*- 83.2 XR 2,381,835 8/ 1945 Moorhead20083.2 2,873,328 2/1959 Hajny 200 -8 3 XR ROBERT K. SOHAEFER, PrimaryExaminer.

H. BURKS, Assistant Examiner,

